Field of the Invention
The present invention relates to an energy absorber that is produced by injection-molding a fiber-reinforced thermoplastic, and a bumper structural body wherein such energy absorbers are mounted on a bumper beam.
Description of the Related Art
Generally, a bumper beam attached to each of the front and rear portions of an automobile body or the like is combined with energy absorbers mounted thereon, making up a bumper structural body. When an impact load is applied to the energy absorbers, they are compressively fractured, thereby absorbing the applied energy.
As disclosed in Japanese Laid-Open Patent Publication No. 08-177922, for example, it is known in the art that a fiber-reinforced thermoplastic (FRTP) which is lighter in weight and easier to mold than metals or the like is used as the material of an energy absorber.
The bumper structural body is mounted on a vehicle body such that the bumper beam extends along the transverse directions of the vehicle body and the energy absorbers have their main portions extending along the longitudinal directions of the vehicle body.
Specifically, the main portions of the energy absorbers have respective ends attached to the bumper beam and respective other ends attached to a frame or the like of the vehicle body. The bumper beam is thus positioned on and fixed to the vehicle body such that ends of the bumper beam in the extending direction are supported by the energy absorbers.
A load is primarily applied to the bumper structural body along a longitudinal direction of the vehicle body. In this case, the bumper beam is deformed thereby to absorb the energy. When the bumper beam is deformed, a tensile load is applied to the energy absorbers supporting the bumper beam, along the extending direction of the bumper beam. If a load in excess of the energy that can be absorbed by the deformation of the bumper beam is applied to the bumper structural body, then the load is transmitted from the bumper beam to the energy absorbers, which absorb the energy by being compressively fractured.
Japanese Laid-Open Patent Publication No. 2007-015626, for example, discloses a bumper structural body wherein energy absorbers made of FRTP are mounted on a bumper beam.